Metal castings are heat treated to allow the components of the casting to diffuse uniformly throughout the casting. The length of time for heat treatment is dependent on the size and shape of the casting, the metal(s) and other additives included in the casting, and as well as other factors. For this reason, facilities with many furnaces will operate them for different heat-treating time periods. Often, castings are transported by rail to and from the furnace. Because of the inflexibility of railroad tracks, it can be difficult to schedule and move castings into and out of furnaces, especially when heat treating times can very. In addition, it becomes difficult to utilize furnaces to full capacity over time when heat treating times vary for different castings.